Percussive ignition type photoflash lamps in general use a hermetically sealed light-transmitting envelope usually made of glass and containing a combustion supporting gas such as oxygen and a loosely distributed filling of a suitable light-producing combustible material such as a shredded foil of zirconium, aluminum, or hafnium, for example, which, on ignition, produces a high intensity flash of actinic light. The ignition means for this type photoflash lamp in general comprises a charge of percussively sensitive fulminating primer material which is located within a readily deformable metal ignition tube sealed within and projecting from one end of a length of glass tubing which forms the lamp envelope and the other end of which is constricted and tipped off. The ignition tube extends generally axially of the tubular lamp envelope and opens thereinto, and the primer material is in the form of a coating on a wire anvil member supported within the ignition tube and extending approximately axially thereof. Flashing of such constructed percussive type photoflash lamp is initiated by a forceful mechanical impact or blow applied against the side of the metal ignition tube to deform it inwardly against the coating of fulminating material on the wire anvil to cause deflagration of the fulminating primer material up through the ignition tube and into the lamp envelope where it then ignites the filamentary combustible material disposed therein. A percussive ignition type photoflash lamp of the above described type is disclosed in U.S. Pat. No. 3,717,432 which includes a wire anvil member having an integral deflector shield for deflecting toward the side of the lamp envelope the hot particles of the primer material upon ignition and wherein said anvil member can further include integral protuberances for coaxial spacing of said anvil member within the metal ignition tube. Specifically, a pair of anvil centralizing lobes are provided by flattening the wire anvil at two closely adjacent points along the length of the anvil and in two different planes at approximately right angles to one another. Additionally, said anvil member is constructed of a suitable metallic composition of high temperature resistance and low thermal conductivity such as, for example, a stainless steel to resist melting or other forms of thermal failure upon flash lamp ignition.
In the above referenced co-pending patent application, there is described an improved wire anvil construction having a plurality of rib elements and a specially shaped lower protuberance to promote central alignment of the anvil in the metal ignition tube. The deflection collar element of said improved anvil has an uninterrupted circular contour for uniform deflection of the hot primer particles entering the lamp envelope. It has been found that the hot particles tend to become extinguished upon impingement with said collar element which gives rise to insufficient burning particles being available to reliably ignite the principal combustible material contained in the lamp envelope.